Gravity angle meter for dental radiography



. inating possibility of distorting Patented Apr. 10, 1923.

STATES FATENT @FFEQE.

LOY E. HARRIS AND TROY A. LEACH, OF EMPORIA, KANSAS.

GRAVITY ANGLE METER FOR DENTAL RADIOGRAPHY.

Application filed March 3, 1922. Serial No. 540,799.

T all whom it may concern:

Be it known that we, LOY E. HARRIS and Tuor A. LnAoH, citizens of the United States, residing at Emporia, in the county of Lyon, State of Kansas, have invented a new and useful Gravity Angle Meter for Dental Radiography, of which the following is the description.

The present invention consists of a. gravit-y angle meter which is especially adapted for use in dental X-ray work.

The principal objects of this invention are to provide an instrument which automatical ly operates to indicate the angle at which a.

film is disposed in the mouth of a patient; to positively prevent bending of a film in the area of the shadow ofthe tooth thereby elimthe shadow; to mechanically produce definite angles thereby eliminating conjecture as to the position of the film; to provide a device of this character which is effective in use even though the teeth are rial-formed or dis aligned; and to provide a device of simple construction which is complete and comprehensive per se and does not require the use of charts, or depend upon other-means to function in the manner above set forth; otherobject s of the invention will no doubt be apparent from the following description of the present preferred form of the invention taken in connection with the accompanying drawings wherein v Fig. l is front elevational view of a de vice constructed in accordance with this invention illustrating its application;

Fi 2 is a rear perspective view of the angle meter per se;

Fig. 3 is a fragmentary perspective view of the invention;

Fig. 4 is a longitudinal sectional view thereof;

Fig. 5 is a vertical sectional view taken through the film holder and illustrating the application of the invention; and

Fig. 6 is a similar view showing the film holder in a different position.

The device of this invention consists of a film holder or bite block generally designated 7 This bite block is preferably made of aluminum or some similar durable though light material the base 8 of which is preferably of an oblong configuration and is provided with grooves 9 in its terminals. One terminal has one of the faces thereof thickened to provide a mount 10.

, tractor and lies -cess 21 as shown A wall 11 rises from said mount at right anformed in said mount which is preferably 2' circular in cross section and is in communication with a tapering way or throat 13 through which the film pack 14 is passed to permit one of the margins thereof to engage said channel 12. The base 8 of the bite block is equipped with a rubber covering 15 engageable by the teeth to facilitate retention of the film holder between the teeth. The device'of this invention consists more especially of a gravity angle meter generally designated 16 and comprising a protractor 17 which carries the usual or any desired indicia. The front face of the protractor is equipped with resilient bar 18 the ends of which are secured on said protractou The back face of the protra-ctor carries a reinforcing plate 19 a portion of the lower margin of which extends downwardly as indicated at 20 and is bent inwardly at right angles below the lowermargin of the proflush with the front face of the latter. The portion 20 of said reinforcing plate 19 has a recess formed therein which registers with a recess formed in the lower marginal edge of said protractor at the front of the latter to provide a reto advantage in Fig. 4. The reinforcing plate 19 is formed to provide a socket 22 which extends outwardly from the protractor 17 at rightv angles to the latter. This socket is adapted to receive one end of a bar 22,"the opposite end of the latter being formed to provide a forked end 23 the furcations of which are slidable in the grooves 9 of the bite block.

An indicating arm 24 is provided one end of which tapers to a point toprovide a pointer movable across the face of the pro-' tractor. Pintles 25 are formed on said arm and are engageable with the recess 21 of the protractor and reinforcing plate and with a recess 26 formed on the inner face of the bar 18. Since the bar 18 is resilient, it will be apparent that the pintles 25 may be sprung into their respective recesses. The lower end of the arm 24 is weighted as indicated at 27 so as to cause the arm to move on its axis thereby causing its pointed end to move across the face of the pro-tractor in accordance. with the angie of disposition of the latter.

In use of this device the bite block is positioned between the teeth of the patient and the film disposed parallel with the longitudinal axis of the tooth as near as possible so as to cast the shadow of the latter on that portion of the film which lies directly in front of the wall 11. It is well known in the art that the. X-ray tube must be positioned at right angles to the film in order to obtain a good and useful radiograph. The position of the bite block of course controls the position ot the angle meter. The right angle to the film is the basis from which the angle of the tube must be determined, governed by the angle between the longitudinal axis of the tooth and the film. The nearer parallel the film and the longitudinal. axis of the tooth the less deviation from the right angle for the position of the X-ray tube. The relative angles that the tube, teeth, and film must occupy in order that the K-rays produce a shadow. of the same length as that of the tooth itself, depends upon a certain law, namely;-that of the bisection of the angle between the long axis of the tooth and of the film and lowering the tube to this amount below the right angle for the upper teeth and raising it the same amount above the right angle for the lower teeth. Consequently, the angle of repose of the film is immediately and automatically depicted upon the protractor so that immaterial of the position of the film in the mouth of the patient, the X-ray tube may be disposed, at the proper angle thereto so as to produce an undistorted radiograph. Therefore, true pictures or radiographs of the teeth may be obtained immaterial of the position of the latter. The device is complete in itself and eliminates the use of other means for showing the angle at which the film is disposed. Moreover, the device is very simple in construction and may be made very small so as to eliminate possibility of inconvenience or annoyance to the patient. With this device it is unnecessary for the patients head to be retained in a vertical position and the device is equally applicable for front or back, up per or lower teeth. In Fig. 5, the device of: this invention is shown as applied to an upper tooth while in Fig. 6 the device is shown as applied to a lower tooth. By making the channels 12 ot the bite block circular in cross section the marginal edges of the film, beyond the margin of the wall 11 may be flexed if necessary. Also, by tapering the throat 13 the film pack may be expeditiously inserted in the channel but accidental displacement of the pack is eliminated.

It is apparent that various changes may be made in this device especially in the details of construction proportion and arrangement of parts within the scope of the claims appended hereto.

What is claimed is 1. A device of the character described including a film carrier engageable between the teeth, and means carried by said carrier to automatically indicate the exact angle of disposition of the film.

2. A device as specified including a film holder, and a gravity angle meter engaged with said holder and automatically operable to depict the to estimate the angle at which the tooth is inclined.

3. A device as set forth including a film holder provided with grooves and equipped with a. film engaging wall to prevent bending of the film in the area of the shadow of the tooth, and means mounted in said grooves to 'show the angle at which the film is disposed.

i. A device of the character described including a film holder engageable between the teeth, a gravity angle meter carried by said holder, and including a protractor and a gravity operated pointer to automatically indicate the position of said film holder.

LOY E. HARRIS. TROY A. LEACH.

angle of repose of the film and 

